Add non-null check

Closes #783

.github/workflows/test.yml

@@ -240,6 +240,18 @@ jobs:
           ruby-version: '2.6'
       - run: ruby -v
 
+  testNoGemfileWithBundlerCache:
+    name: "Test with no Gemfile but with bundler-cache"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: rm Gemfile
+      - uses: ./
+        with:
+          ruby-version: '2.6'
+          bundler-cache: true
+      - run: ruby -v
+
   testLatestRubygemsVersion:
     name: "Test rubygems: latest on ${{ matrix.ruby }}"
     runs-on: ubuntu-latest

dist/index.js

@@ -85351,8 +85351,10 @@ async function setupRuby(options = {}) {
     await common.time('bundle install', async () =>
       bundler.bundleInstall(gemfile, lockFile, platform, engine, version, bundlerVersion, inputs['cache-version']))
 
-    await core.group(`Print lockfile`, async () =>
+    if (lockFile !== null && fs.existsSync(lockFile)) {
-      await exec.exec('cat', [lockFile]))
+      await core.group(`Print lockfile`, async () =>
+        await exec.exec('cat', [lockFile]))
+    }
   }
 
   core.setOutput('ruby-prefix', rubyPrefix)

index.js

@@ -100,8 +100,10 @@ export async function setupRuby(options = {}) {
     await common.time('bundle install', async () =>
       bundler.bundleInstall(gemfile, lockFile, platform, engine, version, bundlerVersion, inputs['cache-version']))
 
-    await core.group(`Print lockfile`, async () =>
+    if (lockFile !== null && fs.existsSync(lockFile)) {
-      await exec.exec('cat', [lockFile]))
+      await core.group(`Print lockfile`, async () =>
+        await exec.exec('cat', [lockFile]))
+    }
   }
 
   core.setOutput('ruby-prefix', rubyPrefix)